MAGNETIC RESONANCE IMAGING APPARATUS AND GRADIENT COIL COOLING CONTROL METHOD

• US 20130038328A1
• Filed: 10/04/2012
• Published: 02/14/2013
• Est. Priority Date: 10/03/2008
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Original Assignee: Toshiba Medical Systems Corporation (Canon Inc.), Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yoshida, Tomoyuki, Nogami, Kazuto, Sakakura, Yoshitomo, IWASA, Masateru, Kojima, Fumitoshi, Adachi, Kohei
• Granted Patent: US 8,564,292 B2
• Time in Patent Office: Days
• US Class Current: 324/309
• CPC Class Codes: G01R 33/3804 Additional hardware for cooling or heating of the magnet assembly, for housing a cooled or heated part of the magnet assembly or for temperature control of the magnet assembly
• CPC Class Codes: G01R 33/3856 Means for cooling the gradient coils or thermal shielding of the gradient coils
• CPC Class Codes: G01R 33/3873 using ferromagnetic bodies ; Passive shimming

Abstract

A feedforward control unit predicts the maximum value of the temperature of a gradient coil based on a power duty and a scan time of a pulse sequence, and a present temperature of the gradient coil. When the maximum value exceeds a predetermined upper limit, the feedforward control unit then instructs a temperature adjusting unit to start a water circulation in a chiller at the start of a prescan, and the temperature adjusting unit starts the water circulation based on the instruction.

Claims

1. A magnetic resonance imaging apparatus comprising:

a gradient coil that applies a gradient magnetic field onto a subject placed in a static magnetic field;

a chiller that cools the gradient coil; and

a control unit that controls the chiller, wherein

the gradient coil includes

a main coil that generates the gradient magnetic field, and

a shield coil that cancels a magnetic field leaking to an outside of the main coil, and

the control unit controls the chiller based on a power duty of a current to be supplied to the main coil and the shield coil, the power duty being determined from scanning parameters of a pulse sequence to be used for a scan of the subject.

2. The apparatus according to claim 1, wherein the control unit controls the chiller at one of a start of a prescan to be performed prior to a main scan according to a predetermined imaging method, and a predetermined time before a start of the prescan.

3. The apparatus according to claim 2, wherein

the predetermined imaging method is echo planar imaging by which a plurality of echo signals for one image is collected by continuously inversing a readout gradient magnetic field with respect to one time of nuclear magnetic excitation, and

the echo signals are collected during the prescan without applying a phase-encoding gradient magnetic field.

4. The apparatus according to claim 1, wherein the control unit predicts a calorific value of the gradient coil based on the power duty, and controls the chiller based on the predicted calorific value.

5. The apparatus according to claim 2, wherein the control unit predicts a calorific value of the gradient coil based on the power duty, and controls the chiller based on the predicted calorific value.

6. The apparatus according to claim 3, wherein the control unit predicts a calorific value of the gradient coil based on the power duty, and controls the chiller based on the predicted calorific value.

7. The apparatus according to claim 1, wherein the control unit predicts a calorific value of the gradient coil based on the power duty and a scan time, and controls the chiller based on the predicted calorific value.

8. The apparatus according to claim 2, wherein the control unit predicts a calorific value of the gradient coil based on the power duty and a scan time, and controls the chiller based on the predicted calorific value.

9. The apparatus according to claim 3, wherein the control unit predicts a calorific value of the gradient coil based on the power duty and a scan time, and controls the chiller based on the predicted calorific value.

10. The apparatus according to claim 1, wherein the control unit predicts a maximum value of a temperature of the gradient coil during a scan, and controls the chiller when the predicted maximum value is equal to or higher than a predetermined upper limit.

11. The apparatus according to claim 2, wherein the control unit predicts a maximum value of a temperature of the gradient coil during a scan, and controls the chiller when the predicted maximum value is equal to or higher than a predetermined upper limit.

12. The apparatus according to claim 3, wherein the control unit predicts a maximum value of a temperature of the gradient coil during a scan, and controls the chiller when the predicted maximum value is equal to or higher than a predetermined upper limit.

13. The apparatus according to claim 4, wherein the control unit predicts a maximum value of a temperature of the gradient coil during a scan, and controls the chiller when the predicted maximum value is equal to or higher than a predetermined upper limit.

14. The apparatus according to claim 5, wherein the control unit predicts a maximum value of a temperature of the gradient coil during a scan, and controls the chiller when the predicted maximum value is equal to or higher than a predetermined upper limit.

15. The apparatus according to claim 6, wherein the control unit predicts a maximum value of a temperature of the gradient coil during a scan, and controls the chiller when the predicted maximum value is equal to or higher than a predetermined upper limit.

16. The apparatus according to claim 7, wherein the control unit predicts a maximum value of a temperature of the gradient coil during a scan, and controls the chiller when the predicted maximum value is equal to or higher than a predetermined upper limit.

17. The apparatus according to claim 8, wherein the control unit predicts a maximum value of a temperature of the gradient coil during a scan, and controls the chiller when the predicted maximum value is equal to or higher than a predetermined upper limit.

18. The gradient coil cooling control method comprising:

acquiring a power duty of a current to be supplied to a main coil and a shield coil included in a gradient coil that applies a gradient magnetic field onto a subject placed in a static magnetic field, based on scanning parameters of a pulse sequence to be used for a scan of the subject; and

controlling a chiller that cools the gradient coil, based on the acquired power duty.